“A song that helps you clear your head”
I’ve definitely listened to “Kimi wa Boku ni Niteiru” by See-Saw for that purpose more than a few times.
This song is the last and best ending song from Gundam SEED Destiny.
(uploaded by RoadSideSkipper09)
Oh, and Studio Megaane’s 8-bit version of this with digitized vocals by Yukako Hayami is amazing in its own right.